BS motor

[Roscoe Poe]

Got a 8 hp B&S motor on a woodspliter and I have to take spark plug out and put some gas in it before it will start. Sometime it will cut
off right after it starts and again it will run. Cleaned carb. and it got gas going to carb.

 

[Anonymous-0]

you need to replace the fuel pump diapghram on the side of the carb.

 

[JT]

Might have an intake valve not seating, or intake gasket leaking, if you took off carb, cleaned and rebuilt correctly. Or engine could just be worn out and does not have enough vacumn to pull gas into cylinder until it starts.
8HP Briggs don't have a diaphram on side of carb.
Jim

 

[Kevin2]

Do a compression check. I'll bet you find only 60 psi or so. Valves need work.

 

[Anonymous-0]

From New Haven?

 

[Anonymous-0]

From New Haven?

 

[Anonymous-0]

Are you using fresh gas?

Stale gas = hard to start.

 

[Goose]

We once had a 5.5 hp BS on a lawn mower. It had the same problem from day one. Never did figure it out. One day I got pi$$ed off, went to Wheelers farm store and bought a new replacement engine. It started reliably on the second pull for years.

Maybe you just got a contankerous one like I did.

 

[Don Collison]

Isn,t that what a choke is for??

 

[Anonymous-0]

crankshaft seal no vacuum no suck gas

 

[Joho]

Pull the main jet out, its a long needle like jet. Be sure it is clean. Use some small wire to get in the holes. I had that problem, old gas left some scaley residue in there and it blocked the jet holes even after I rebuilt the carb. I thought I had it clean but after I saw the scaley stuff I guess I didn't have it as clean as it should be. Worked fine after that.

 

[micro]

Jt great post.

Also as far as doing a compression test on these small motors, They have a compression release built onto the cam, thus B&S states that all that they need is 30 psi compression to work.

A good way to test compression without any tools is to simply remove the spark plug and place your finger or thumb over the spark plug hole in the head (keeping spark plug wire out of the way and grounded.) If the compression is enough to blow your finger off the hole, is is plenty of compression. If not, then you definitely have a problem as jt and others have posted. You can also try turning out (counter clockwise) Your high speed and perhaps your low speed jet a little bit. (high speed is on bottom of carb. Low speed is on top and side of carb).

Also with the long jet joho was talking about. You need to remove that long jet to disassemble the two halves of the carburetor any way. Or could break, then you have to buy a $20 kit just to get the jet.

 

[trucker40]

Im not a small engine mechanic,but I have heard a small engine mechanic say that on those motors the valves usually are whats wrong with them.They run and the springs pull the valves deeper into the seats.This causes the clearance to be less and less to where the valve is not opening enough to run right,or maybe not closing good.Whichever way it is if you figure out how to get the clearance right it probably will run better.

 

[Brian Jasper co. Ia]

That would be on a 2 stroke. The 8hp B&S is a four stroke.

 

[Brian Jasper co. Ia]

Trucker40 is pretty close. I collect antique small engines and find 95% of them need the valves reground to restore compression. You can't take a compression reading on an "Easy Spin" Briggs due to the compression release on the intake lobe of the cam. On those engines, Briggs States that "A sharp rebound turning the engine backwards denotes acceptable compression".
The diaphragm on the side of the carb would be on smaller 5hp and 3hp engines with a Pulsa-Jet carb and a horizontal crankshaft. On these carbs the diaphragm is only for a fuel pump to fill a small cup in the fuel tank under the carb. The cup is used so the fuel mixture screw does not need to be changed as the fuel level in the tank drops.

 

[Anonymous-0]

Tighten the carb where it bolts on to the motor. B & S are noted for that. Ive played that game so often, I could write a book on B & S. I have three concrete tools that viborate in a very extreem maner. I simply can't keep those carbs from falling off. If I use lock tite, or drill the stud bolt and wire it, they break off.

The small engine folks hide in the corner when I show up, and often a cement truck is sitting at the job site to add to the fun.

The last round we found a screw in the butterfly inside the carb. That was a scream, a (28 cy slab) and a power trowler that would not start easy, and died at least thirty times...but always somehow started with enough pulls.